Stress Fractures
The majority of stress fractures take place in the lower limbs (approx. 80-90%), and are very common in runners (incidence being approx. 16% of all running injuries) because of the high loads placed on these limbs.
It can take anywhere from 1 month to 1 year for a stress fracture to heal, so it is important to understand them, and how to best avoid them.
Most people think of stress fractures occurring in the tibia (shin bone) (which is most common in runners) or the metatarsals (bones that come just before the toes), but they can also occur in the navicular (foot bone) and most common in sprinters, femur (thigh bone), and pelvis.
In school, we were always taught of a simple way to think of stress fracture pathology:
1. A bone can be healthy but have undue stress, causing a stress fracture
Or…
2. A bone can be unhealthy but have regular stresses placed upon it, causing a stress fracture
There are 2 main mechanisms that cause a stress fracture
1. Overuse
and/or
2. Overload
Formula: Stress > Rate of bone repair leads to a stress fracture
Multiple “micro” fractures become “macro” fractures requiring early diagnosis (which is not as easy as it may seem!)
Stress fracture signs/symptoms:
Injury usually occurs at the end of activity and is “insidious” (meaning a patient will come in saying “I have no clue what happened, there was no mechanism of my injury!”)
LOCAL pain and/or swelling and/or tenderness
More pain when placing weight on the structure
An important question to ask yourself, and for me to ask you during a history, is "has the pain become more frequent?" i.e. occasional pain during running or activity, persistent pain during running or activity or pain throughout the day during regular movement.
Remember stress fracture occurs from overuse or overload, so it is important to ask if you have gained weight recently, changed your regular physical activity regimen (ex:// your running surface: outdoor to indoor, etc), have been doing more repetitive exercise with less rest, or have had any recent injury or trauma.
The best way so far is to classify stress fracture as either high or low risk
High risk: “High risk fractures typically require surgical repair based on a likelihood that the stress fracture will progress to a complete fracture, delayed union or nonunion, or requires assisted/nonweight-bearing.”
Low risk: “Low risk stress fractures generally respond to conservative treatment.”
Fortunately, the most common stress fracture sin runners, as previously mentioned, is in the tibia (shin bone), but these are usually low risk
Imaging (best of the best = MRI) is important for proper diagnosis and risk evaluation.
MRI is considered “gold standard” in terms of imaging, because it shows bone edema, one of the earliest signs of a stress fracture and not often seen on regular x ray imaging. X ray imaging may not show signs of a stress fracture until 2-3 weeks into the fracture, and are therefore not good for acute stress fracture injury.
Prevention: strengthen your plantarflexors (weakness in these à less force dissipationà undue stress on the metatarsals leading to a stress fracture of these bones.
Treatment:
Rest
Immobilization
Reduction in load bearing activities
Surgery
Magical number for healing time with conservative care = approx. 8 weeks.
Risk factors:
Smoking
Irregular menstrual cycles
Females with irregular nutrition
Caucasian
Sport type (distance/endurance running)
Conservative Therapy Rehab: Phase 1
Rest
Maintaining aerobic fitness
Modalities
Oral pain medications: WARNING: DO NOT USE NSAIDS AS THEY ACTUALLY SLOW BONE HEALING
Weight bearing activity is ok (within tolerance) but running is not advised! Good alternatives to keep up cardiovascular health but diminish heavy impact include biking,
“The first phase of a conservative rehabilitation protocol includes rest of the anatomical site, maintenance of aerobic fitness, physical therapy modalities, and oral analgesics… other than nonsteroidal anti-inflammatory drugs, which potentially slow bone healing… Phase one should include weight-bearing as tolerated and ambulation modification if needed, yet running should be avoided. Likewise, minimal-impact activities to maintain cardiovascular fitness should be initiated, such as cycling, pool running, antigravity treadmill running, cycling, and swimming.”
Conservative Therapy Rehab: Phase 2
Should occur 2 weeks after pain free in ambulation and cross training and no more local tenderness
Things to include:
muscle endurance
core stability
pelvic stability : these 3 things 2-3X/week using full body training
balance/proprioception
retraining of gait
flexibility
Running should get back to pre-injury level gradually (over 3-6 weeks) and should be supervised by a medical practitioner who will monitor pain recurrence.
Starting running at approximately 30-50% of preinjury status and then progressing 10% per week is a general guideline in getting back to full running capacity.
It can take anywhere from 61 to approximately 131 days to return back to full running participation depending on the fracture grade (low or high) and the risk of fracture (low or high)
Patient Advice:
Early return to running before one is ready can be very detrimental and may even result in a full-blown fracture.
Cross training will be an important part of rehab to keep up one’s fitness, but allow time for fracture healing. An example is water running.
Hills and continued changes in terrain can be risk factors for stress fracture, as can increasing running mileage.
Orthotics may be preventive to injury as they help absorb shock
Changing your shoes approx. every 6 months (approx. 300-500 miles i.e. 780-1300km) can also help in regards to receiving proper shock absorption during running
Though still uncertain, vitamin D (800-1000IU) and calcium (1500-2000mg) may be protective factors to stress fracture
Other factors should be considered for stress fracture injury predisposition, some of which include inquiry into female athlete triad (eating disorder, osteoporosis and amenorrhea (not receiving your period), osteopenia or osteoporosis, menstrual irregularities, etc. should be inquired into.
References: Kahanov L, Eberman LE, Games KE, Wasik M. Diagnosis, treatment and rehabilitation of stress fractures in the lower extremity in runners. Open Access Journal of Sports Medicine. 2015 Mar 27; 6:87-95.
